<?php
//two 3x3 matrix for practice
$A=array(array(1,2,1), array(0,1,2), array(3,0,-1));
$B=array(array(-1,1,1), array(3,1,0), array (2,1,-1));
$C=array(array(), array(), array()); //matrix fot reutrning results

function add_sub($M1, $M2, $i)
{
    $w=$M1+($i*$M2);
    return $w;
}

function sub($M1, $M2)
{
    add_sub($M1, $M2, -1);
}

function add($M1, $M2)
{
    add_sub($M1, $M2, 1);
}

$x=5;
$y=3;
$z=add($x, $y);
echo "add function: $z <br>";
echo "sub function: ".sub($x, $y)."<br>";

?>